With motor generators such as a motor and electrical generator used in an electric vehicle or hybrid vehicle or the like, coils generate heat due to iron loss and resistance, and so cooling means that use air cooling or a cooling medium are provided in a motor generator. However, in a motor generator heat is generated due to prolonged use and excessive load, etc., and there are cases of overheating when cooling using a cooling medium is insufficient. Conventionally, therefore, temperature of each section of the motor generator is measured, and control is carried out such that in the event that a measured temperature exceeds a predetermined temperature the load on the motor generator is limited, or the motor generator is stopped.
Generally, with motor generators for vehicles, motor generators of inverter controlled three-phase alternating current type are often used. Since this type of motor generator is integrally mounted in a vehicle together with an engine and a transmission, a method for cooling by circulating oil, which is a cooling medium, inside the motor generator is adopted. In the case of measuring temperature of the motor generator, a method of measuring the temperature of coil end sections, where the coils are exposed from slots in the stator core, is easy, and so coil end temperature measurement is often used. However, there have been situations where if a temperature sensor is attached to a coil end section or the like, a measured temperature is higher or lower than the actual temperature due to oil that spills onto the temperature sensor.
Accordingly, patent document 1 discloses technology for carrying out measurement of coil end section with good precision, while simultaneously attempting to reduce the size of a motor generator for a vehicle, by protecting an insulating layer for an outer surface of a neutral point fixed to a coil end section of a motor generator for a vehicle. Also, patent document 2 discloses a motor generator that prevents positional slip of a temperature sensor fixed to a coil end section, and in which a coil is molded using resin with the object of protecting the coil, having a temperature sensor that is inserted into a hole formed in a resin section.